Return-path: Received: from he.sipsolutions.net ([78.46.109.217]:52063 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758256Ab2GFVFg (ORCPT ); Fri, 6 Jul 2012 17:05:36 -0400 From: Johannes Berg To: linux-wireless@vger.kernel.org Cc: Johannes Berg Subject: [RFC 1/3] mac80211: make scan_sdata pointer usable with RCU Date: Fri, 6 Jul 2012 23:05:31 +0200 Message-Id: <1341608733-7503-2-git-send-email-johannes@sipsolutions.net> (sfid-20120706_230541_009879_89203C90) In-Reply-To: <1341608733-7503-1-git-send-email-johannes@sipsolutions.net> References: <1341608733-7503-1-git-send-email-johannes@sipsolutions.net> Sender: linux-wireless-owner@vger.kernel.org List-ID: From: Johannes Berg Making the scan_sdata pointer usable with RCU makes it possible to dereference it in the RX path to see if a received frame actually matches the interface that is scanning. This is just preparations, making the pointer __rcu. Signed-off-by: Johannes Berg --- net/mac80211/ieee80211_i.h | 2 +- net/mac80211/iface.c | 9 +++++---- net/mac80211/scan.c | 33 ++++++++++++++++++++++++--------- 3 files changed, 30 insertions(+), 14 deletions(-) diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h index b0830ae..da66a73 100644 --- a/net/mac80211/ieee80211_i.h +++ b/net/mac80211/ieee80211_i.h @@ -974,7 +974,7 @@ struct ieee80211_local { unsigned long leave_oper_channel_time; enum mac80211_scan_state next_scan_state; struct delayed_work scan_work; - struct ieee80211_sub_if_data *scan_sdata; + struct ieee80211_sub_if_data __rcu *scan_sdata; enum nl80211_channel_type _oper_channel_type; struct ieee80211_channel *oper_channel, *csa_channel; diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c index c4c20cf7..43e1052 100644 --- a/net/mac80211/iface.c +++ b/net/mac80211/iface.c @@ -112,10 +112,11 @@ static u32 __ieee80211_recalc_idle(struct ieee80211_local *local) } } - if (local->scan_sdata && - !(local->hw.flags & IEEE80211_HW_SCAN_WHILE_IDLE)) { + sdata = rcu_dereference_protected(local->scan_sdata, + lockdep_is_held(&local->mtx)); + if (sdata && !(local->hw.flags & IEEE80211_HW_SCAN_WHILE_IDLE)) { scanning = true; - local->scan_sdata->vif.bss_conf.idle = false; + sdata->vif.bss_conf.idle = false; } list_for_each_entry(sdata, &local->interfaces, list) { @@ -636,7 +637,7 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata, clear_bit(SDATA_STATE_RUNNING, &sdata->state); - if (local->scan_sdata == sdata) + if (rcu_access_pointer(local->scan_sdata) == sdata) ieee80211_scan_cancel(local); /* diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c index d1b4b9d..48d3219 100644 --- a/net/mac80211/scan.c +++ b/net/mac80211/scan.c @@ -294,7 +294,13 @@ static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted, return; if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) { - int rc = drv_hw_scan(local, local->scan_sdata, local->hw_scan_req); + int rc; + + rc = drv_hw_scan(local, + rcu_dereference_protected(local->scan_sdata, + lockdep_is_held(&local->mtx)), + local->hw_scan_req); + if (rc == 0) return; } @@ -395,7 +401,10 @@ void ieee80211_run_deferred_scan(struct ieee80211_local *local) if (!local->scan_req || local->scanning) return; - if (!ieee80211_can_scan(local, local->scan_sdata)) + if (!ieee80211_can_scan(local, + rcu_dereference_protected( + local->scan_sdata, + lockdep_is_held(&local->mtx)))) return; ieee80211_queue_delayed_work(&local->hw, &local->scan_work, @@ -406,9 +415,12 @@ static void ieee80211_scan_state_send_probe(struct ieee80211_local *local, unsigned long *next_delay) { int i; - struct ieee80211_sub_if_data *sdata = local->scan_sdata; + struct ieee80211_sub_if_data *sdata; enum ieee80211_band band = local->hw.conf.channel->band; + sdata = rcu_dereference_protected(local->scan_sdata, + lockdep_is_held(&local->mtx));; + for (i = 0; i < local->scan_req->n_ssids; i++) ieee80211_send_probe_req( sdata, NULL, @@ -440,7 +452,7 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata, if (!ieee80211_can_scan(local, sdata)) { /* wait for the work to finish/time out */ local->scan_req = req; - local->scan_sdata = sdata; + rcu_assign_pointer(local->scan_sdata, sdata); return 0; } @@ -474,7 +486,7 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata, } local->scan_req = req; - local->scan_sdata = sdata; + rcu_assign_pointer(local->scan_sdata, sdata); if (local->ops->hw_scan) { __set_bit(SCAN_HW_SCANNING, &local->scanning); @@ -534,7 +546,7 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata, ieee80211_recalc_idle(local); local->scan_req = NULL; - local->scan_sdata = NULL; + rcu_assign_pointer(local->scan_sdata, NULL); } return rc; @@ -721,7 +733,8 @@ void ieee80211_scan_work(struct work_struct *work) mutex_lock(&local->mtx); - sdata = local->scan_sdata; + sdata = rcu_dereference_protected(local->scan_sdata, + lockdep_is_held(&local->mtx)); /* When scanning on-channel, the first-callback means completed. */ if (test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning)) { @@ -742,7 +755,7 @@ void ieee80211_scan_work(struct work_struct *work) int rc; local->scan_req = NULL; - local->scan_sdata = NULL; + rcu_assign_pointer(local->scan_sdata, NULL); rc = __ieee80211_start_scan(sdata, req); if (rc) { @@ -894,7 +907,9 @@ void ieee80211_scan_cancel(struct ieee80211_local *local) if (test_bit(SCAN_HW_SCANNING, &local->scanning)) { if (local->ops->cancel_hw_scan) - drv_cancel_hw_scan(local, local->scan_sdata); + drv_cancel_hw_scan(local, + rcu_dereference_protected(local->scan_sdata, + lockdep_is_held(&local->mtx))); goto out; } -- 1.7.10.4